Several methods, such as incineration disposal, crushing sterilization by medicament disposal, sterilization by autoclave heat disposal, microwave ashing disposal, high-temperature plasma disposal, etc., have been proposed as a disposal method of infectious medical wastes, but these proposals involve the following problems and cannot be said to be adequate.
While the incineration disposal being a typical disposal method of infectious medical wastes has a feature that when medical wastes are incinerated, only ash remains and the disposal is very high in rate of volume reduction, a secondary combustion furnace, a waste gas quench apparatus, an electrical dust precipitator, a bag filter, a device for analysis and monitoring of exhaust gases, etc. are essential in order to prevent generation of dioxin, and in the case where these devices are not provided, a serious problem from the view point of environmental protection and energy activation remains in a sense that there is a fear of great atmospheric pollution caused by a large amount of hydrogen chloride gas generated from vinyl chloride resin contained in medical wastes and medical wastes being valuable in energy recycling are incinerated wastefully.
Also, the crushing sterilization by medicament disposal involves a serious problem from the view point of reliability in sterilization and environmental protection since there is a fear that pathogenic bacteria contained in medical wastes scatter into the atmosphere when medical wastes are crushed, even when it is tried to crush medical wastes to subject them to sterilization by medicament, the possibility of sure sterilization of pathogenic bacteria existent in fluid infusion tubes or the like is not guaranteed, and there is a fear that medical wastes being minutely crushed in a reclaimed disposal site are scattered by wind to forest land and farmland.
Further, the sterilization by autoclave heat disposal is thought in the light of Pascal's formula to enable materializing uniform pressure and uniform temperature in all locations in an autoclave to enable sure sterilization of medical wastes but involves a serious problem from the view point of reliability in sterilization and working environment since it is heard from the scene that sterilization cannot be completely accomplished and grotesque medical wastes are handled after the sterilization disposal while being in the original form.
Also, the microwave ashing disposal makes use of the principle of home electronic oven but cannot be said to be an actual disposal in terms of increased installation cost since the disposal is not only low in processing capacity but also a waste gas processing device is essential like the incineration disposal described above, to say nothing of ensuring the corrosion resistance for the apparatus, since a large amount of hydrogen chloride gas is generated when vinyl chloride wastes contained in medical wastes are subjected to ashing disposal.
Further, the high-temperature plasma disposal cannot be said to be an actual disposal in terms of increased installation cost since not only the operation of an apparatus in temperature as high as 3000° C. needs a high operation technology but also a waste gas processing device is essential like the incineration disposal described above, to say nothing of ensuring the corrosion resistance for the apparatus, since a large amount of hydrogen chloride gas is generated when vinyl chloride wastes contained in medical wastes are subjected to plasma disposal.
Further, in order to solve a problem involved in a heating and melting system or crushing sterilization by medicament system disposal method for infectious medical wastes, JP-A-7-88140 discloses a disposal apparatus for making medical wastes harmless, the apparatus comprising a substrate, from which medical wastes are forwarded in the form of compact cake, a housing provided on the substrate and having a discharge passage of cake, an upright cylinder arranged on the housing and provided with a charging port for medical wastes and a swingable push lid, a first piston unit provided on the cylinder and having a piston, which compresses medical wastes into cake, a second piston unit provided on the substrate and having a moving plate for opening and closing of a drop port of the cylinder, and an evaporation unit arranged on the substrate below the housing.
Also, JP-U-6-42819 discloses, as a bucket conveyor obtained by improving a conveyor, a bucket conveyor, in which a drive shaft provided at both ends thereof with driving wheels is borne at one end of a base frame, a driven shaft provided at both ends thereof with driven wheels is borne at the other end of the base frame, one end of the drive shaft is connected to a motor through a reduction device, L-shaped partition plates, respectively, are mounted in opposite and back to back manner to an upper surface of an endless belt, which turns in a manner of enabling stepping rotation, between the driving wheels and the driven wheels, side plates, respectively, are mounted on both side upper portions of the base frame in a manner to substantially contact both ends of the partition plates, and notches, which are shaped to agree with the cross sectional shape of a basket portion defined by a pair of the partition plates, are provided at one ends of the both side plates.
Further, in order to solve a problem involved in a disposal method of heating and melting system for infectious medical wastes, JP-A-2001-252345 discloses a disposal apparatus for making medical wastes harmless, the apparatus comprising a bucket conveyor section (3) for transporting a plurality of buckets (2), which store bag bodies (P) receiving therein medical wastes (M), while steppingly rotating them in a predetermined direction, a sterilization by heat section (4, 4a), by which medical wastes stored in a bucket are subjected to sterilization by heat, a compression disposal section (5), by which medical wastes having been subjected to sterilization by heat are compressed in a position after the sterilization by heat section to make a cake-like substance (C), and a discharge section (7) for discharge of the cake-like substance from the compression disposal section, the apparatus having a feature that a bag body with medical wastes received therein is received in the bucket (2) positioned inside side plates (9) arranged in a traveling direction of the bucket conveyor section (3), a plurality of heat feed pipes (23) having a plurality of small holes on peripheral surfaces of lower portions thereof and exhaust pipes (25) are provided in a track of the bucket conveyor section, a hot air blasting device (24) is provided on the heat feed pipes, and the heat feed pipes and the exhaust pipes are pushed down by a hydraulic cylinder to blow a hot blast from the heat feed pipes, which are pierced into the bag body, to accomplish sterilization by heat.
Also, in order to solve that matter, in which when heating-compressing means is used to subject medical wastes generated in medical institutions to sterilization-volume reduction, the wastes are caused by pressure to adhere to a heating element, which comprises heating means, to make discharge difficult, JP-U-3126377 discloses a disposed product discharging mechanism in a medical wastes disposal apparatus comprising a disposal cylinder (4), a piston (13) provided with means, which goes up and down in the disposal cylinder (4), and having an electric heater (14), and a gate (16) provided with means, which opens and closes a lower end opening of the disposal cylinder (4), and having an electric heater (17), the mechanism having a feature that after medical wastes are subjected to sterilization volume reduction by heating compression, the gate (16) is fully opened to lower a lower end surface of the electric heater (14) of the piston (13) to an upper end surface of the electric heater (17) of the gate (16) to fully close the gate (16) and a disposed product adhering to the electric heater (14) of the piston (13) is mechanically scraped off.